An explicit delamination propagation algorithm to simulate delamination growth under quasi-static and fatigue loading without re-meshing using virtual crack closure technique and progressive nodal release

A modeling approach is proposed to simulate delamination propagation in composite laminates under both quasi-static and fatigue loading regimes. Delamination growth is simulated using the Virtual Crack Closure Technique combined with a progressive nodal release strategy. In the proposed approach, the delamination propagation increment is determined explicitly, based on the energy release rate calculated in the previous time increment. Explicitly determining the delamination propagation increment linearizes the system of equations that results from the progressive nodal release strategy and eliminates convergence issues associated with delamination growth. In fatigue, the delamination growth increment is calculated using as input growth rates characterized experimentally via fitting of a suitable form of the Paris law to the experimental data. Under quasi-static loading conditions, a sufficiently large pseudo-growth rate is assumed, such that the simulation results converge to the results obtained with the chosen binary (growth/no growth) fracture criterion. Since both fatigue and quasi-static loading regimes share the same underlying algorithm, simulating the transition between fatigue and quasi-static delamination growth is trivial. The approach is demonstrated to accurately simulate delamination growth for all cases assessed, including quasi-static mixed-mode loading and the transition between fatigue and quasi-static delamination growth regimes. Finally, it is also shown that the approach can simulate both self-similar and non-self-similar delamination growth.